Environmental meteorological parameters (temperature, humidity, air pressure, etc.) have an important impact on short gap streamer discharge. Based on the streamer theory and particle continuity equation of gas discharge, a short gap streamer discharge simulation model is established, and the influence of environmental parameters on the dynamic development process of streamer discharge is simulated and analyzed. The short gap air gap discharge characteristics were tested in a self-made gas discharge chamber. The results show that at low humidity (relative humidity 80%), with the increase of humidity, the electron density of the streamer channel decreases, the field strength of the streamer head decreases, the development speed of the streamer slows down, and the gap breakdown voltage increase. With a decrease of gas pressure, the electron density of the streamer channel decreases, the field strength of the streamer head decreases, the development speed of the streamer increases, and the gap breakdown voltage decreases; The temperature change has little effect on the streamer development process.

In this study, the gas-sensing mechanism of ZnO, TiO2, and Ag2O modified SnS2 toward dissolved gases (CO, CH4, C2H2, and C2H4) in transformer oil were studied based on the density functional theory. The modified structure, adsorption structure, band structure, adsorption energy, charge transfer, deformation charge density, density of states, and molecular orbit were analyzed. The results show that the conductivity of SnS2 monolayer is improved to a certain extent after surface modification with ZnO, TiO2, and Ag2O. And the adsorption of CO, CH4, C2H2, and C2H4 on the intrinsic SnS2 monolayer is weak physical adsorption. Compared with the intrinsic substrate, the adsorption energies of MO-SnS2 (M=Zn, Ti, Ag2) monolayer for the four target gases have been increased to different degrees, except that the adsorption energy of TiO2-SnS2 for C2H4 molecule has decreased slightly. With deformation charge density, density of states and molecular orbital analysis, it can be concluded that ZnO-SnS2 and TiO2-SnS2 have good gas sensitivity to CO, C2H2, and C2H4 molecules, and Ag2O-SnS2 also has strong adsorption capacity to C2H2 and C2H4 molecules. This work provides a theoretical basis for the application of gas sensors used in oil-immersed transformers.

Ice-shedding jumps in transmission lines often lead to accidents such as flashover and tower collapse. Existing mitigation methods typically require the application of additional external equipment on conductors. In this study, the inhibitory effect of load current cycling transferred ice-melting technology (LCCT) on bundled conductors is investigated to eliminate the need for supplementary devices. The underlying principles are analyzed, a numerical simulation model is developed, and field experiments are conducted under natural environmental conditions. The results demonstrate that the inhibitory effect varies significantly with changes in the ice thickness and ice-melting conditions. For ice thicknesses ranging from 5 mm to 25 mm under identical melting conditions, the inhibitory effect increases by 67.8%. The most effective inhibition (93.4% average) occurs at the 25-mm ice thickness. Among the ice-melting conditions, H4 has the greatest inhibitory effect (95.4%). Other conditions yield inhibitory effects ranging from 2.6% to 76.2%. Field experiments confirm that condition H4 achieves a 91.4% inhibitory effect on four-split transmission lines.

Unclean air discharge refers to the discharge phenomenon of a large number of polluting gases, droplets or solid particles floating in the air, which will cause insulation breakdown and safety accidents for the power transmission equipment that have been left outdoors for a long time. In order to investigate the effects of particle concentration, particle size and dielectric constant on DC breakdown characteristics of unclean air gap, a self‐made discharge chamber was designed in this study. The air was filtered and passed into the discharge chamber to remove the influence of impurities contained in the air on the experimental results. Then, solid particles with different concentration, particle size and particle dielectric constant were added to the discharge chamber to carry out the DC positive polarity breakdown characteristic experiment. The experimental results show that compared with dry clean air, the presence of solid particle increases the breakdown voltage of the gap, and the increase proportion of breakdown voltage is related to the particle concentration, particle size and particle dielectric constant. With the same particle type and particle size, the increase proportion of breakdown voltage increases with the higher concentration, which up to 10.49%. For further investigating, the fluid mechanics model was selected to simulate the process of streamer discharge in unclean air. The results show that compared with dry clean air, the presence of particles enhances the gap discharge ionisation process, but also enhances the adsorption of particles, and the latter has stronger effect than the former, thus increases the gap breakdown voltage. At the same time, the enhancement of adsorption effect increases the electric field intensity of the gap and speeds up the development process of streamer discharge.

Icing torsion of overhead single conductors exacerbates conductors icing, posing a serious threat to the power grid's operation. Few methods exist to suppress icing torsion and reduce the risk of icing damage to the power grid. This paper observes and analyzes the icing torsion of single conductor in the field natural environment, establishing the mathematical-physical model for icing torsion of overhead single conductors. A novel approach involving the application of orthogonal moments to the conductor is proposed to enhance its equivalent torsional stiffness and then suppress icing torsion. The effectiveness of this suppression method is quantified by the effective suppression interval ratio, the maximum suppression rate of icing torsion angle, and the icing torsion angle decrease ratio. Taking the LGJ-400/35 overhead single conductor as object, the field natural experiments on suppressing its icing torsion were conducted. The results demonstrate that the method proposed significantly suppresses the icing torsion of overhead single conductor, with an effective suppression interval ratio of 100%, a maximum suppression rate of icing torsion angle exceeding 90%, and the icing torsion angle decrease ratio surpassing 88%.